This invention relates to a functionalized polyphenylene ether resin useful as a plastic material in the fields of electrical and electronic products, automobiles and other industrial materials, and foods and packaging fields and to a process of producing the same.
Polyphenylene ethers are excellent in processability and productivity. They can be molded by melt injection, melt extrusion and similar molding techniques into products or parts of desired shapes with good productivity. Therefore they have been widely used as a material of products and parts in the electrical and electronic fields, automobile field, and other industrial materials fields, and foods and packaging fields.
In the electrical and electronic fields, automobile field and other various industrial fields, products and parts have now come to be widely diverse, and requirements for resin materials therefor have also been diversified. To meet the requirements, polymer composite (combination of existing polymers with other materials) technology and polymer alloy (combination of existing polymers) technology have led to resin materials with characteristics not possessed by existing materials.
General polyphenylene ethers, while excellent in heat resistance and mechanical characteristics, have poor compatibility with other materials, and the choice of materials to be combined with is limited. They have particularly poor compatibility with highly polar materials such as polyamide and need to be functionalized to be combined with such resins.
With respect to functionalized polyphenylene ethers, JP-B-3-52486, U.S. Pat. Nos. 4,654,405 and 4,888,397, and JP-A-63-54425 propose processes in which polyphenylene ether in a molten state is allowed to react with a reactive functionalizer, such as maleic anhydride, in the presence or absence of a radical initiator. However, the proposed processes involve very high temperatures for melting the resin, which cause various problems arising from thermal deterioration of the resin, such as color change, formation of black gel, and poor color tone or appearance.
European Patent 546497, JP-A-4-239036, and JP-A-3-35020 teach processes in which a mixture of polyphenylene ether and a functionalizer, such as maleic anhydride, in a prescribed mixing ratio is allowed to react in a solvent capable of dissolving polyphenylene ether. These processes achieve only a low functionalization reaction rate and, besides, resin compositions obtained by blending the resulting functionalized polyphenylene ether with different polymers are of low utility as a material due to their inferior mechanical characteristics.
JP-A-2-276823 discloses polyphenylene ether with a 6-chroman end group to which a functional group, e.g., a carboxyl group or an oxidized acyl group, is bonded. In all the working Examples given, however, polyphenylene ether is melted at a high temperature (300xc2x0 C. or 320xc2x0 C.). The resulting functionalized polyphenylene ether resins were found to have a poor color tone and to contain considerable black foreign substance which is a scorched resin.
JP-A-12-191769 and WO 00/52074 disclose a process of obtaining functionalized polyphenylene ether by allowing polyphenylene ether in a solid state to react with a functionalizing compound. According to the disclosed process, because the reaction is preceded by mixing polyphenylene ether with a solid or liquid functionalizing compound in a predetermined ratio, the functionalization reaction rate is extremely low so that resin compositions obtained by blending the resulting functionalized polyphenylene ether and different polymers have inferior mechanical characteristics and low practicability as a material.
JP-B-63-7204 proposes supplying a radical polymerizable compound in a gaseous phase to polyphenylene ether in the presence of an organic or inorganic radical polymerization initiator. The process involves the problem that the functionalizing compound itself is apt to homopolymerize, failing to be added to polyphenylene ether efficiently.
As mentioned above, functionalized polyphenylene ether resins obtained by conventional techniques have an unsatisfactory balance between color or appearance and mechanical properties for sufficiently fulfilling the demands of industrial fields.
The present invention relates to a functionalized polyphenylene ether which has an excellent color tone, contains little black foreign substance, and provides polymer alloys with superior mechanical characteristics when blended with other resins.